The complete or partial detachment of ligaments, tendons and/or other soft tissues from their associated bones within the body are relatively commonplace injuries, particularly among athletes. Such injuries are generally the result of excessive stresses being placed on these tissues. By way of example, tissue detachment may occur as the result of an accident such as a fall, over-exertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities. In the case of a partial detachment, the injury will frequently heal itself, if given sufficient time and if care is taken not to expose the injury to further undue stress. In the case of complete detachment, however, surgery may be needed to re-attach the soft tissue to its associated bone or bones.
Numerous devices are currently available to re-attach soft tissue to bone. Examples of such currently-available devices include screws, staples, suture anchors, and tacks. In soft tissue re-attachment procedures utilizing screws, the detached soft tissue is typically moved back into its original position over the bone. Then the screw is screwed through the soft tissue and into the bone, with the shank and head of the screw holding the soft tissue to the bone. Similarly, in soft tissue re-attachment procedures utilizing staples, the detached soft tissue is typically moved back into its original position over the bone. Then the staple is driven through the soft tissue and into the bone, with the legs and bridge of the staple holding the soft tissue to the bone.
In soft tissue re-attachment procedures utilizing suture anchors, an anchor-receiving hole is generally first drilled in the bone at the desired point of tissue re-attachment. A suture anchor is then deployed in the hole using an appropriate installation tool. This effectively locks the suture, with soft tissue attached thereto.
While suture anchors provide an effective, minimally-invasive technique for soft tissue repair, it is desirable to utilize an anchor having a small diameter so as to avoid unnecessary trauma. The size of the anchor, however, can be limited by the size of the suture and/or the bending stiffness of the suture. Typically, a single strand of repair suture is folded and trailing ends of the suture are attached to a threader loop, which is used to pull the folded suture into the anchor. When a folded suture is used, the cannulated portion of the anchor must be large enough to accommodate at least two times the thickness of the repair suture. The bending stiffness of the repair suture used can also limit the size of the anchor. For example, high strength suture can have a greater bending stiffness than other types of suture and this can make it difficult to bring legs of the suture together to form a 180° fold, especially near the location of the bend. Because a width at the bend is larger than a width of two legs of the suture, it can be difficult to fit the bend in a lumen in the anchor. This in turn restricts the ability to reduce the size of the anchor.
Accordingly, there remains a need for improved methods and devices for attaching soft tissue to bone.